1. Field of the Invention
The invention relates to packaging films. More particularly, the invention pertains case ready packaging films having good antifog performance that are suitable for use in meat packaging.
2. Description of the Related Art
Containers have long been used to store perishable foods, such as meats, fruits and vegetables, prior to sale in the marketplace to consumers. Maximizing the time in which the food remains preserved in the containers minimizes the amount of spoilage.
The environment around which the food is preserved is an important factor in the preservation process. It is important that the food is maintained at an adequate temperature, while also controlling the molecular and chemical content of the gases surrounding the food. By providing an appropriate gas content to the environment surrounding the food, the food can be better preserved when maintained at the proper temperature or even when it is exposed to variations in temperature. This gives the food producer some assurance that the food will be in an acceptable condition when it reaches the consumer. Preferred modified atmosphere packaging systems for foods, including raw meats, exposes these foods to extremely low levels of oxygen because it is well known that the freshness of meat can be preserved longer under anaerobic conditions than under aerobic conditions. Maintaining low levels of oxygen minimizes the growth and multiplication of aerobic bacteria. Additionally, modified atmosphere packaging can involve high levels of oxygen, e.g. 80%, combined with nitrogen and/or carbon dioxide. The gases in these combinations do not favor bacterial growth but allow the raw meat to maintain a preferred red color that is acceptable to the consumer.
It is also important that the packaging exhibit good resistance to the formation of condensation inside the package on a surface of the film. This is known in the art as an antifog property. Multilayered films for modified atmosphere packaging having such antifog properties are well known and are commonly used when packaging food products having a high moisture content, such as fresh meats, and when it is important for the product to be clearly visible to the consumer. For example, U.S. Pat. Nos. 5,766,772, 5,567,533 and 5,520,764 describe multi-layer heat-shrinkable films endowed with antifog properties having a different structure from this invention.
To produce a film exhibiting this antifog property, an antifog component is typically blended with or coated onto a sealant film such as a polyethylene film. This antifog-polyethylene component then forms a part of a multilayered packaging film, such as a nylon packaging film, that may also incorporate an oxygen barrier polymer layer such as ethylene vinyl alcohol. However, one significant problem associated with such known multilayered films having this antifog component is that the antifog component tends to be drawn toward polar materials, such as nylon, and away from the non-polar polyethylene. This is particularly a problem when the film is rolled up after manufacture such that the antifog layer or antifog containing polyethylene layer is brought into direct contact with an adjacent nylon layer. This causes the antifog component to migrate out of its existing polyethylene layer and into the nylon layer, compromising the performance of the nylon layer as well as degrading the antifog property of the film. Therefore, it would be desirable to have a multilayered packaging film having good antifog performance and having an antifog component which does not migrate into adjacent nylon layers when stored. The present invention provides such a solution to this need.
The invention provides a multilayered film comprising an outer film attached to an inner film, wherein:
A) the outer film comprises:
i. a first nylon layer having first and second surfaces;
ii. an oxygen barrier layer having first and second surfaces, with its first surface attached to the second surface of the first nylon layer;
iii. a second nylon layer having first and second surfaces, with its first surface attached to the second surface of the oxygen barrier layer; and
B) the inner film comprises:
i. a third nylon layer having first and second surfaces;
ii. a silicone oil coated onto the first surface of or blended into the third nylon layer; and
iii. a sealant film on the second surface of the third nylon layer, which sealant film either contains an antifog composition, or has an antifog composition coated on a surface thereof; and
wherein the second nylon layer is laminated to the third nylon layer via an intermediate adhesive layer, such that the second surface of the second nylon layer and the first surface of the third nylon layer are facing each other.
The invention also comprises a multilayered film comprising an outer film attached to an inner film, wherein:
A) the outer film comprises:
i. a first nylon 6 layer having first and second surfaces; 5 ii. an ethylene vinyl alcohol layer having first and second surfaces, with its first surface attached to the second surface of the first nylon layer;
iii. a second nylon 6 layer having first and second surfaces, with its first surface attached to the second surface of the ethylene vinyl alcohol layer; and
B) the inner film comprises:
i. a third nylon 6 layer having first and second surfaces;
ii. a silicone oil coated onto the first surface of or blended into the third nylon 6 layer; and
iii. a sealant film on the second surface of the third nylon 6 layer, which sealant film comprises at least one polyethylene layer, which the at least said one polyethylene layer either contains an antifog composition, or has an antifog composition coated on a surface thereof; and
wherein the second nylon 6 layer is laminated to the third nylon 6 layer via an intermediate adhesive layer, such that the second surface of the second nylon 6 layer and the first surface of the third nylon 6 layer are facing each other.
In addition, this invention provides a food package which comprises a container having an open portion and a multilayered film sealing the open portion, wherein the multilayered film is as described above.
The invention further provides a process for forming a multilayered film comprising:
a) forming an outer film comprising a first nylon layer, an oxygen barrier layer and a second nylon layer, wherein the oxygen barrier layer is between the nylon layers;
b) forming an inner film which comprises a third nylon layer having first and second surfaces, a silicone oil coated on the first surface of or blended into the third nylon layer, and a sealant film on the second surface of the third nylon layer, which sealant film either contains an antifog composition, or has an antifog composition coated on a surface thereof; and
c) laminating the outer film to the inner film via an intermediate adhesive layer, such that the second nylon layer and the first surface of the third nylon layer are facing each other.
This invention still further provides a process for forming a multilayered film comprising:
a) forming an outer film which comprises:
i. a first nylon layer having first and second surfaces;
ii. an ethylene vinyl alcohol layer having first and second surfaces, the first surface of the ethylene vinyl alcohol layer attached to the second surface of the first nylon layer; and
iii. a second nylon layer attached to the second surface of the ethylene vinyl alcohol layer;
b) forming an inner film which comprises:
i. forming a third nylon layer having first and second surfaces;
iii. a second nylon layer attached to the second surface of the ethylene vinyl alcohol layer,
b) forming an inner film which comprises:
i. forming a third nylon layer having first and second surfaces;
ii. coating a silicone oil onto the first surface of the third nylon layer;
iii. attaching a sealant film onto the second surface of the third nylon layer, which sealant film comprises at least one polyethylene layer, which at least one polyethylene layer either contains an antifog composition, or has an antifog composition coated on a surface thereof; and
c) attaching the second nylon layer to the third nylon layer such that the first surface of the third nylon layer faces the second nylon layer.
The invention therefore provides a desirable multilayered packaging film and a roll thereof having good physical properties, good antifog performance and having an antifog component which does not migrate into adjacent nylon layers when stored.